Four ways. Your ways += a spread protractor instead of an angle protractor. [1] There's a spread protractor link in the bottom section of the page. Stuart Morrow 02:09, 22 January 2009 (UTC)

Five ways: another unit of angular measure is the grad, 1/400th of a circle. wikipedia-- Davewa 17:11, 22 January 2009 (UTC)

And how about having a text box somewhere where kids can store down numbers (the lengths or angle measurements)? This way, a kid could summon (resume) the "measurement of his lunch box" activity.
Grreat idea! And having now done it for Stopwatch, it should be easy. Thanks! MitchellNCharity 13:52, 9 September 2007 (EDT)
Hi! I'm testing your ruler on a b-4, it' great, here are some ideas and comments:

It seems to be very accurate, I measured a postcard with a ruler and with Rule, and it was only different in less than half a milimeter.

I think you could join the centimeter and milimeter grid on the same window. It would be divided by half, the top part showed milimeters, and the bottom showed centimeter. Kids still have the wide horizontal length of the display, and still get the understanding that 1 centimeter is 10 milimeter.

What if you made each milimeter vertical line be colorized as the cursor passes through it, givinng on a box the current measurement (from the left edge to that vertical line), and when the kid clicks once, it gets saved as a measurement, in the future Rule measurements log. And in tablet mode, the same would happen, but using the directional buttons, and X game key to save the measurement (it's easier to measure having it in tablet mode, in a horizontal plane).

Anyway, Rule already works as intended: taking the limitation of the screen, it let's the kid take distance measurements of objects which are shorter than the horizontal width of the screen!

I'll later test with different paper thickness the possibility to draw on it or measuring drawings in it, by covering the screen with the sheet of paper. HoboPrimate 14:28, 14 September 2007 (EDT)

In the future, though, probably Sugar should support a second type of applications, installable "floating" Tools, which the user could install and use in any activities. This way, a kid could just use the Ruler within Write to measure and write down the measurements, or use it in Paint to create a drawing with specific measurements. HoboPrimate 11:12, 11 August 2007 (EDT)

A related thought is encouraging people to make widgets available. For example, I should create reusable python code for drawing rules and grids. And, from Stopwatch, for draggable widgets. It would be nice if, say, a music program could reuse the programming blocks in Turtle Art; the turtle could draw in Paint; a math exploration program, could reuse parts of the calculator; etc, etc. So the unit of security and activity could still be the Activity, but there's a library of components to build on. I don't really know what the olpc vision for components and libraries is. MitchellNCharity 13:52, 9 September 2007 (EDT)

Maine and Massachusetts both need that other measurement system. (as does the rest of the USA, along with Liberia, and anybody following instructions written in those places) AlbertCahalan 11:59, 11 August 2007 (EDT)

Do they? If so, when a deployment there is impending, Imperial units might be added. If they can't be talked out of it. MitchellNCharity 13:52, 9 September 2007 (EDT)

Yes. Supposedly Maine and Massachusetts are currently green status. Liberia is currently "plan to include in the post-launch phase" (the almost-green color, which is red for some odd reason). While I understand that many people do find US Customary and Imperial measurement to be gross, it is something that many kids must learn to deal with. AlbertCahalan 01:38, 14 September 2007 (EDT)

Implementation Discussion

The measurements are wrong by a factor of sqrt(2) because the numbers run along a diagonal. A 10 cm object will be measured as 7 cm. AlbertCahalan 11:59, 11 August 2007 (EDT)

The numbers apply to the horizontal/vertical directions. Doing it this way is an attempt to generate discussion/thought. Limited (extremely) user testing suggests kids do indeed, spot, think about, and figure it out. The next draft should make it somewhat clearer (by continuing the labels horizontally (11-15 cm)). Then we'll see how field experience goes. A diagonal ruler could be overlayed on the graph, to make it even clearer. Thanks for the feedback. MitchellNCharity 13:52, 9 September 2007 (EDT)

How about replacing the grid with concentric circles? Place the center at the upper left or upper right. Then you have easy measurement across the diagonal of the screen, which is longer than either edge. There is also no likely way to screw things up. AlbertCahalan 01:38, 14 September 2007 (EDT)

Very good point, this way you coud measure longer things. (and make each circle light up as the cursor passes over it, see my suggestion above). HoboPrimate 14:32, 14 September 2007 (EDT)